S-type fuse holder

ABSTRACT

An S-type fuse holder designed to simplify and speed up assembly, and to reduce the number and cost of its component parts, in which the center and ring contact elements are combined with their associated terminals and are thereafter simultaneously snapped into the holder body for permanent assembly therewith. The center and ring contacts are insertable from the same direction, and upon insertion snap into place after they are inserted to approximately the same extent, in a manner to permit permanent and simultaneous assembly thereof with the body by a single stroke of an assembly tool.

United States Patent Inventor Kenneth H. Walterick Levittown, Pa. Appl. No. 22,879 Filed Mar. 26, 1970 Patented Nov. 23, 1971 Assignee Circle F Industries, Inc.

S-TYPE FUSE HOLDER 1 Claim, 7 Drawing Figs.

US. Cl 337/216, 337/226 Int. Cl H01h 85/24, HO l h 85/52 Field of Search 337/186, 187, 191, 192, 194, 195, 200, 216, 226; 339/97 L, 99 L, 217 S Primary Examiner- Bernard A. Gilheany Assistant E.taminer Dewitt M. Morgan Attorney-Sperry and Zoda ABSTRACT: An S-type fuse holder designed to simplify and speed up assembly, and to reduce the number and cost of its component parts, in which the center and ring contact elements are combined with their associated terminals and are thereafter simultaneously snapped into the holder body for permanent assembly therewith. The center and ring contacts are insertable from the same direction, and upon insertion snap into place after they are inserted to approximately the same extent, in a manner to permit permanent and simultaneous assembly thereof with the body by a single stroke of an assembly tool,

PATENTEUuuv 23 197i 3,622,931

SHEET 2 BF 2 A T'TO ILH EYE,

BACKGROUND OF INVENTION 1. Field of Invention The invention pertains to the art of manufacture of fuse holders, in particular fuse holders, not of the adapter type, for S- type fuses.

2. Description of the Prior Art S-type fuse holders are all of standard or like construction in a sense that each must have a body of electrically insulative material having a threaded recess, a center contact, and a ring contact formed with a serrated thread. By reason of this construction, the fuse holder is adapted to receive a standard S- type fuse. The center and ring contacts are provided with terminals for connection in the fused circuit.

The most recent examples of prior art are Bienwald et al. U.S. Pat. No. 3,444,498 issued May 13, I969; and Sebastian, U.S. Pat. No. 3,497,851 issued Feb. 24, I970. Since as indicated above, all S-type fuse holders must conform with one another in respect to the basic essentials enumerated above, the patentees have been primarily concerned with improved construction features for S-type fuse holders, to facilitate manufacture, mounting, or the interchange with older devices of the same general type. Thus, in U.S. Pat. No. 3,497,851, the main object has been to reduce the total number of parts to a minimum, and permit assembly without such separate fasteners as screws, rivets, or the like.

It is thus apparent that in light of the fact that all S-type fuse holders have basic characteristics in common, the main problems in the art derive from manufacturing costs. In the highly competitive wiring device industry, even a seemingly infinitesimal reduction in manufacturing cost produces a competitive advantage, therefore, when one considers the great volume in which such devices are produced.

In other words, given a situation, as is true here, in which all devices must meet certain, very rigid dimensional requirements and performance tests prescribed by Underwriters Laboratories and various governmental authorities, the future course of development in the art generally lies primarily in the designing of such devices in a way that meets said requirements while reducing manufacturing costs, even to a very slight degree, below those costs dictated by the designs settled upon by competitors in the industry.

The present invention aims, by a novel concept, to provide an S-type fuse holder that can be manufactured at a cost lower than those fuse holders previously designed for the same purpose as exemplified by the patents named above and by the following additional patents known to applicant:

SUMMARY OF THE INVENTION Summarized briefly, the invention includes a body of electrically insulative material, as for example a high heat phenolic resin. The body has a central, threaded recess, a bottom aperture opening into the recess through the bottom of the body, and a pair of diametrically opposed side openings formed in a collar or flange adjacent the open end of the recess. A center contact is of inverted L shape, and seats in the bottom of the recess to provide a contact button integral with a depending leg extending through the bottom aperture and terminating in a male terminal. A ring contact includes a ring member seating in the open end of the recess, and having a single, serrated thread. Holding the ring member in place is a retaining ring contact, which as diametrically opposed legs extending into the side openings. One of these is elongated to provide a ring contact terminal.

The legs of the center contact and of the ring contact are formed with lanced-out tongues, resiliently tensioned to snap under and interlock with lugs or projections formed on the walls of the center aperture and side openings. The construction is such as to facilitate assembly of the device from one direction, in such a manner that a single stroke of an assembly tool, such as an ordinary kick press, simultaneously snaps into place both the center contact and the ring contact. Assembly of the center and ring contacts with the body is thus achieved in a single simple operation that can involve one short, light stroke ofa punch. Thus, not only are rivets or similar fastening elements eliminated, but also, it is unnecessary to resort to crimping such as in the above-mentioned U.S. Pat. No. 3,497,851 or other more complex, slower assembly procedures.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view ofa fuse holder according to the present invention;

FIG. 2 is an enlarged longitudinal section substantially on line 2-2 of FIG. I;

FIG. 3 is a bottom plan view of the device as seen from line 33 of FIG. 2;

FIG. 4 is a top plan view;

FIG. 5 is a longitudinal section substantially on line 5-5 of FIG. 4;

FIG. 6 is a longitudinal section substantially on line 66 of FIG. 4; and

FIG. 7 is a longitudinal sectional view illustrating the manner in which the contacts may be assembled with the body, substantially on line 7-7 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing in detail, the S-type fuse holder constituting the present invention includes a body generally designated 10, formed of electrically insulative material such as a high heat phenolic resin to include a generally cylindrical main portion 12 having an upwardly opening center recess 14 formed with molded threads 16 to receive an S-type fuse, not shown. At the open end of the recess, the body is formed with an enlarged circumferential flange or collar 18, defining a circumferential, downwardly facing external shoulder 20 adjacent the upper end of the body, and an upwardly facing internal shoulder 22 extending about a shallow counterbore 24 which in turn merges into a counterbore 26 of recess 14.

Diametrically opposed openings 28 (FIG. 5) are formed in body 10, outwardly from recess 14, communicating between internal shoulder 22 and longitudinal side recesses 30 of main portion 12.

A ring member 32, as required in an S-type fuse, has a single thread 33 pitched as a continuation of thread 16. Ring member 32, in accordance with the requirements of Underwriters Laboratories, is of hardened steel, and as shown in FIG. 4, has teeth or serrations 35 formed in thread 33 thereof.

Ring member 32 has an outwardly directed lip 37 seating in the shallow recess 24. To prevent rotation of ring member 32, said member is formed (See FIG. 4) with an outwardly projecting tab 34 seating in a complementary recess 36 of body 10 communicating with the shallow counterbore 24 in a plane common to said shallow counterbore.

Overlying ring member 32 is a ring contact member 38 formed with an annular, flat body 39 overlying lip 37 of member 32, and integral with an elongated first leg 40 having intermediate its ends a Ianced-out locking tab or abutment 42 adapted to snap under and interlock with a locking lug 44 formed on the wall of opening 28 through which leg 40 extends. The leg extends into recess 30, where it is formed as a male tab or terminal 41, and in a preferred embodiment, the male terminal is bent outwardly slightly as in FIG. 5 to facilitate connection of a mating female connector, not shown, thereto.

Diametrically opposite leg 40, the ring contact member 38 is formed with a shorter leg 48, having a lanced-out abutment 50 adapted to snap under and interlock with a locking lug 44 of the opening 28 in which leg 48 is positioned.

Openings 28, recesses 30, and lugs 44 are identical with each other at diametrically opposite locations on the body, and abutments 42, 50 are at corresponding locations on legs 40, 48 respectively, so as to eliminate the necessity of the as sembler pairing a particular leg of the ring contact with a particular side opening 28 ofthe body.

The members 32, 38 together constitute a ring contact generally designated 52.

Member 38 is formed of a suitable copper alloy such as brass, in accordance with requirements for S-type fuse holders, and it is for this reason that members 38 and 32 must usually be formed as separate and distinct members assembled as shown in the drawing or in patents such as Bienwald et al. U.S. Pat. No. 3,444,498. Alternatively, such members would have to be initially separately formed and then brazed together if they are to be offered as a one-piece member such as in Sebastian U.S. Pat. No. 3,497,851.

lntegrally formed at the closed end of body is an insulating barrier 54 interposed between an end aperture 56 of the body and a diametrically extending, shallow bottom recess 58 of the body that receives the bight 60 of a steel snap-in mounting spring 62 having resiliently deflectable legs 64 the upper ends 66 of which are retained in recesses 68 formed in shoulder 20. Spaced drive screws 70 secure spring 62 to body 10.

A snap-in spring of the type described is conventionally employed in many wiring devices, and constitutes no part of the present invention. Alternatively, the body could be formed with diametrically opposed, apertured cars such as shown for example in Sebastian U.S. Pat. No. 3,497,851, receiving mounting screws or the like if a snap-in spring mounting arrangement is not desired.

A center contact 72 is formed with a contact button 73 (FIGS. 4 and 6), integral with an elongated leg 74 projecting through and beyond aperture 56 to terminate in a male tab or terminal 76. A lanced out locking tongue 78 on leg 74 is resiliently, yieldably tensioned to pass a locking projection 80 formed on one wall of aperture 56, during assembly, after which tongue 78 snaps under projection 80 to interlock therewith as in FIG. 6 to permanently assemble the center contact with the body.

The transverse dimension of aperture 56 is such that in the finally assembled position of the center contact, the leg 74 bears against the wall of the aperture opposite the wall on which projection 80 is formed, so that it is impossible to so deform the leg 74 during attachment of a female connector, as to disengage the tongue 78 from projection 80.

It will be readily apparent that the construction illustrated and described permits the assembly of the center and ring contact means with the insulating body at a complete minimum of cost. This is shown in FIG. 7. In this figure of the drawing, the member 32 has been dropped into place in the shallow counterbore 24, the center contact has been dropped into place with its leg 74 extending through aperture 56, and member 38 has been dropped into place with its legs 40, 48 disposed in openings 28. Due to the presence of lugs 44 and projection 80, the center contact and the member 38 will initially be supported equal distances above the bottom of recess 14 and the shoulder 22, respectively.

The body would be positioned in a suitable assembly jig J, as shown in FIG. 7 after which a punch P, capable of operation by a kick press or equivalent assembling machinery, is brought down, with an enlarged portion A thereof being formed with a shoulder S bearing against member 38, said shoulder extending about a reduced portion B the end of which bears against the center contact 72. Portions A, B, as will be apparent, may engage the member 38 and the center contact substantially simultaneously, after which a short additional stroke of the assembly tool drives the member 38 and the center contact home, with their locking tongues snapping past their associated, cooperating projections of the body to the finally assembled positions shown in FIGS. 5 and 6.

I claim:

1. An S-type fuse holder comprising:

a. a body of electrical insulation material having a threaded recess opening upon one end of the body for receiving an S-type fuse having a mating thread, the body having a shoulder extending about the center recess at said end, longitudinal side recesses, side openings angularly spaced about the threaded recess in communication between the shoulder and the side recesses, and an end opening communicating between the threaded recess and the other end of the body;

b. a center contact mounted in the end opening and including fuse-contacting means exposed within the threaded recess and terminal means extending exteriorly of the body; and

. a ring contact mounted in the side openings, including annular, serrated, fuse-contacting means exposed within the threaded recess and terminal means extending exteriorly of the body within one of the side recesses, said contacts respectively including flat legs extending through the openings, at least two of the legs providing electrical terminations exteriorly of the body, the legs of both contacts being formed with locking tabs and being tensioned to lie substantially flat against one wall of their associated openings with their locking tabs engaging the opposite wall in interlocking relation with a lug formed on said opposite wall, the lugs of the several openings being equally spaced from one end of the openings whereby to simultaneously assemble with the body both the center and ring contacts responsive to a single stroke of an assembly punch common to both contacts. 

1. An S-type fuse holder comprising: a. a body of electrical insulation material having a threaded recess opening upon one end of the body for receiving an S-type fuse having a mating thread, the body having a shoulder extending about the center recess at said end, longitudinal side recesses, side openings angularly spaced about the threaded recess in communication between the shoulder and the side recesses, and an end opening communicating between the threaded recess and the other end of the body; b. a center contact mounted in the end opening and including fuse-contacting means exposed within the threaded recess and terminal means extending exteriorly of the body; and c. a ring contact mounted in the side openings, including annular, serrated, fuse-contacting means exposed within the threaded recess and terminal means extending exteriorly of the body within one of the side recesses, said contacts respectively including flat legs extending through the openings, at least two of the legs providing electrical terminations exteriorly of the body, the legs of both contacts being formed with locking tabs and being tensioned to lie substantially flat against one wall of their associated openings with their locking tabs engaging the opposite wall in interlocking relation with a lug formed on said opposite wall, the lugs of the several openings being equally spaced from one end of the openings whereby to simultaneously assemble with the body both the center and ring contacts responsive to a single stroke of an assembly punch common to both contacts. 